Ordering too little concrete means a rushed trip to the hardware store. Too much means wasted money. Our concrete calculator helps you get it right the first time.
The Formula
Volume = Length × Width × Depth
For a rectangular slab in feet:
- Cubic feet = L × W × D
- Cubic yards = Cubic feet ÷ 27
Example: 10×10 Patio Slab, 4" Deep
- Length: 10 ft, Width: 10 ft, Depth: 0.33 ft (4")
- Cubic feet: 10 × 10 × 0.33 = 33 cubic ft
- Cubic yards: 33 ÷ 27 = 1.22 cubic yards
How Many Bags?
| Bag Size | Per Cubic Yard | For 1.22 Yards |
|---|---|---|
| 60 lb | 45 bags | ~55 bags |
| 80 lb | 34 bags | ~42 bags |
Types of Concrete Projects
- Slabs: Patios, driveways, floors
- Footings: Foundation support
- Columns: Round or square support posts
- Stairs: Step-by-step calculation
Pro Tips
- Order 10% extra to account for spillage and uneven subgrades
- For ready-mix, order in quarter-yard increments
- Use rebar or wire mesh for slabs larger than 4×4
- Cure slowly — keep concrete moist for at least 7 days
Try Our Concrete Calculator
Our Concrete Calculator makes ordering easy:
- Cubic feet, cubic yards, and cubic meters
- Bag count for 60lb and 80lb bags
- Add 10% waste factor automatically
💡 Pro Tip: For large projects, ready-mix concrete is usually cheaper and more consistent than mixing bags yourself. A truck carries about 10 cubic yards.
*Calculate concrete with our free Concrete Calculator.*
